In 1983, the etiological cause of AIDS was determined to be the human immunodeficiency virus (HIV). In 1985, it was reported that the synthetic nucleoside 3xe2x80x2-azido-3xe2x80x2-deoxythymidine (AZT) inhibits the replication of human immunodeficiency virus. Since then, a number of other synthetic nucleosides, including 2xe2x80x2,3xe2x80x2-dideoxyinosine (DDI), 2xe2x80x2,3xe2x80x2-dideoxycytidine (DDC), and 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydrothymidine (D4T), have been proven to be effective against HIV. After cellular phosphorylation to the 5xe2x80x2-triphosphate by cellular kinases, these synthetic nucleosides are incorporated into a growing strand of viral DNA, causing chain termination due to the absence of the 3xe2x80x2-hydroxyl group. They can also inhibit the viral enzyme reverse transcriptase.
3xe2x80x2-Azido-2xe2x80x2,3xe2x80x2-dideoxyuridine (CS-87) is a known compound. It was originally disclosed as an intermediate in the synthesis of an anti-cancer agent. See, for example, U.S. Pat. No. 5,099,010; Lin et al., J. Med. Chem. 26, 1691-1696 (1983); Lin and Mancini, J. Med Chem. 26, 544-548; and Colla, et al., Eur. J Med. Chem.-Chim. Ther. 295-301 (1985). Later, it was discovered that the compound has significant anti-HIV activity with lower toxicity than AZT. See U.S. Pat. No. 4,916,122 to Chu and Schinazi. The compound was also included in a broad disclosure of 3xe2x80x2-azido-2xe2x80x2,3xe2x80x2-dideoxynucleosides for the treatment of HIV filed by The Wellcome Foundation Limited (see EPA 0 217 580 A2 (Example 64, published Apr. 8, 1987)) and UK Patent Application No. 8622194 (Example 64, published on Apr. 15, 1987). The Wellcome Foundation application included within its broad disclosure a significant number of compounds which do not exhibit activity against HIV or which are too toxic to administer, making it difficult for the reader to identify the useful compounds.
It has been recognized that drug-resistant variants of HIV can emerge after prolonged treatment with an antiviral agent. Drug resistance most typically occurs by mutation of a gene that encodes for an enzyme used in viral replication, and most typically in the case of HIV, reverse transcriptase, protease, or DNA integrase. Recently, it has been demonstrated that the efficacy of a drug against HIV infection can be prolonged, augmented, or restored by administering the compound in combination or alternation with a second, and perhaps third, antiviral compound that induces a different mutation from that caused by the principle drug.
Alternatively, the pharmacokinetics, biodistribution, or other parameter of the drug can be altered by such combination or alternation therapy. In general, combination therapy is typically preferred over alternation therapy because it induces multiple simultaneous pressures on the virus. One cannot predict, however, what mutations will be induced in the HIV-1 genome by a given drug, whether the mutation is permanent or transient, or how an infected cell with a mutated HIV-1 sequence will respond to therapy with other agents in combination or alternation. This is exacerbated by the fact that there is a paucity of data on the kinetics of drug resistance in long-term cell cultures treated with modern antiretroviral agents.
Ronald Rooke, et al. (Antimicrobial Agents and Chemotherapy, May 1991, p. 988-991) describe the isolation of AZT-resistant variants of HIV-1 from patients on long-term drug therapy by primary isolation of virus in the presence of the drug and by showing that frozen samples of HIV-1, first isolated in the absence of drug pressure, were able to replicate efficiently when AZT was added. Their findings disclose that two isolates of HIV-1 may show susceptibility to AZDU (3xe2x80x2-Azido, 2xe2x80x2,3xe2x80x2-dideoxyuridine).
As more anti-HIV drugs are introduced commercially to treat patients infected with HIV, patients are exposed to a variety of drugs to maintain a low titer of virus during the inevitable resistant patterns that develop. This is true because antiviral drugs alter the selective pressure on the virus population. Any preexisting xe2x80x9cresistantxe2x80x9d variant has a growth advantage over wild-type competitors. The numbers of resistant virus will increase relative to wild type virus if replication is permitted to proceed. The emergence of viral drug resistance is recognized as a central problem for the success of current antiviral therapy regimens in HIV-infected patients. Patients can ultimately develop multi-drug resistant HIV which is an incalcitrant form of virus that does not exhibit strong sensitivity to a range of anti-HIV drugs. Patients with multi-drug resistant forms of HIV are particularly hard to treat and will become more numerous in the future. It is a current goal of antiviral therapy to identify compounds and methods to treat patients with multi-drug resistant forms of HIV.
It is an object of the present invention to determine the optimal administration of CS-87 for the treatment of HIV, based on the mutation pattern that it induces in HIV-1.
It is another object of the present invention to provide a method and composition that incdludes CS-87-for the treatment of patients infected with HIV that exhibits advantageous or improved pharmacokinetic, biodistribution, metabolic, resistance or other parameters over administration of CS-87 alone.
It is also an object of the invention to improve the efficacy of CS-87 during short periods of administration and over extended time periods.
It is another object of the invention to assess the sensitivity of HIV-1 to CS-87 in a patient to whom CS-87 has been administered.
It is also an object of this invention to provide a method for treating a patient with a multiple drug resistant form of HIV that includes administering an effective HIV-treatment amount of CS-87 or its prodrug or salt.
It is yet another object of the present invention to provide a method and composition for the treatment of patients infected with HIV in which CS-87 is administered in combination or alternation with a second compound that acts synergistically with CS-87 against the virus.
It is yet another object of the present invention to provide a method and composition for the treatment of patients infected with HIV in which CS-87 is administered in combination or alternation with a second compound that induces a mutation in HIV at a location other than the 70th codon of the reverse transcriptase region of HIV.
It is a further object of the invention to provide pharmaceutical prodrugs and compositions that increase the efficacy of administration of CS-87 for the treatment of patients infected with HIV.
It is another object of the present invention to provide a method and kit for the detection of CS-87 resistant HIV-1.
It has been discovered that CS-87 induces a transient mutation in HIV-1 at the 70th codon (K to R; i.e., lysine to arginine) of the reverse transcriptase region of the virus. Based on this discovery, a method for treating HIV is provided that includes administering CS-87 or its pharmaceutically acceptable salt or prodrug to a human in need of therapy in combination or alternation with a drug that induces a mutation in HIV-1 at a location other than the 70th codon of the reverse transcriptase region. This invention can be practiced by referring to published mutation patterns for known anti-HIV drugs, or by determining the mutation pattern for a new drug.
It was surprising to discover that the mutation induced by CS-87 is transient. This is unusual and allows for long term therapy with CS-87, as the mutated virus exposed to CS-87 over time is converted back to naive virus, which has an increased sensitivity to the drug.
CS-87 thus can be administered in combination with one or more antiviral agents which do not induce a mutation at the 70th codon of the reverse transcriptase region to achieve an advantageous therapeutic effect against HIV. In some cases, the enhanced therapeutic effect is not attainable by administration of either agent alone. In a preferred but not necessary embodiment, the effect of administration of the two or more agents in combination or alternation is synergistic.
In one preferred embodiment, CS-87 is administered in combination with a protease inhibitor. In particular embodiments, CS-87 is administered in combination or alternation with indinavir (Crixivan), nelfinavir ([3S-[2(2S*,3S*),3-alpha,4-a-beta,8a-beta-]]-N-(1,1-dimethylethyl)decahydro-2-)2-hydroxy-3-[(3-hydroxy-2-methylbenzoyl)amino]-4-(phenylthio)butyl]-3-isoquinolincarboxamide mono-methanesulfonate) (Viracept), saquinavir (Invirase), or 141W94 (amprenavir; (S)-tetrahydrofuran-3-yl-N-[(1S,2R)-3-[N-[(4-aminophenyl)sulfonyl]-N-isobutylamino]-1-benzyl-2-hydroxypropyl]carbamate; ritonavir or ABT-378 (N-(4(S)-(2-(2,6-dimethylphenoxy)-acetylamino)-3(S)-hydroxy-5-phenyl-1(S)-benzylpentyl)-3-methyl-2-(S)-(2-oxo(1,3-diazaperhydroxinyl)butanamine.
In another preferred embodiment, CS-87 is administered in combination or alternation with a nucleoside analog, including (xe2x88x92) and racemic FTC, 3TC, D4T, DDI, DDC, or abacavir (1592U89) which is (1S,4R)-4-[2-amino-6-cyclopropyl-amino)-9H-purin-9-yl]-2-cyclopentene-1-methanol succinate; or in combinationor alternation with a nucleotide analogue, including adefovir or PMPA.
In another embodiment, CS-87 is administered in combination with a nonnucleoside reverse transcriptase inhibitor such as DMP-266 (efavirenz; 1,4-dihydro-2H-3, 1-benzoxazin-2-one); delavirdine, (I-[3-(1-methyl-ethyl)amino]-2-pyridinyl-4-[[5-[(methylsulfonyl)amino]-1H-indol-2-yl]carbonyl]-, monoethanesulfonate), or nevirapine.
In other embodiments, CS-87 is administered in combination or alternation with an HIV-integrase inhibitor or a chemokine inhibitor or a fusion inhibitor.
In general, during alternation therapy, an effective dosage of each agent is administered serially, whereas in combination therapy, an effective dosage of two or more agents are administered together. The dosages will depend on such factors as absorption, biodistribution, metabolism and excretion rates for each drug as well as other factors known to those of skill in the art. It is to be noted that dosage values will also vary with the severity of the condition to be alleviated. It is to be further understood that for any particular subject, specific dosage regimens and schedules should be adjusted over time according to the individual need and the professional judgment of the person administering or supervising the administration of the compositions. Examples of suitable dosage ranges for anti-HIV compounds, including nucleoside derivatives (e.g. D4T, DDI, and 3TC) or protease inhibitors, for example, nelfinavir and indinavir, can be found in the scientific literature and in the Physicians Desk Reference. Many examples of suitable dosage ranges for other compounds described herein are also found in public literature or can be identified using known procedures. These dosage ranges can be modified as desired to achieve a desired result.
The disclosed combination and alternation regiments are useful in the prevention and treatment of HIV infections and other related conditions such as AIDS-related complex (ARC), persistent generalized lymphadenopathy (PGL), AIDS-related neurological conditions, anti-HIV antibody positive and HIV-positive conditions, Kaposi""s sarcoma, thrombocytopenia purpurea and opportunistic infections. In addition, these compounds or formulations can be used prophylactically to prevent or retard the progression of clinical illness in individuals who are anti-HIV antibody or HIV-antigen positive or who have been exposed to HIV.
Importantly, it has also been discovered that CS-87 and its prodrugs and pharmaceutically acceptable salts are active (i.e., with an EC50 (also referred to herein as IC50) that is at most less than five fold the EC50 of the drug in wild type virus, and preferably, less than 4, 3, or 2 times the EC50 of the drug in wild type virus) against multiple-drug resistant forms of HIV. As used herein, we define multiple drug resistant HIV as having at least one of the following characteristics: (i) the drug resistant strain is genotypically resistant (greater than five fold resistant and more typically, greater than 10, 50 or 100 fold resistant in a same cell line over wild type virus) to AZT and D4T; (ii) the drug resistant strain is genotypically resistant to 3TC and (-) and racemic FTC; (iii) the drug resistant strain is phenotypically resistant (greater than five fold resistant and more typically, greater than 10, 50 or 100 fold resistant in a same cell line over wild type virus) to HIV strains of virus with mutations at the 41, 215 and 184 codons in the reverse transcriptase region, or at least the 184 with at least the 41 or 215 mutations; (iv) the drug resistant strain is genotypically resistant to at least two protease inhibitors; (v) the drug resistant strain is genotypically resistant to at least two protease inhibitors; (vi) the drug resistant strain is genotypically resistant to at least two non nucleoside reverse transcriptase inhibitors; or (vii) the drug resistant strain is genotypically resistant to at least two nucleoside reverse transcriptase inhibitors.
Therefore, in another important embodiment of this invention, a method for treating a patient with a multiple drug resistant form of HIV is provided that includes administering an effective HIV-treatment amount of CS-87 or its prodrug or salt.
In any of the embodiments described herein, if CS-87 is administered in combination or alternation with a second nucleoside or nonnucleoside reverse transcriptase inhibitor that is phosphorylated to an active form, and for example, the active 3xe2x80x2-triphosphate form, by a kinase enzyme, it is preferred that a second compound be phosphorylated by an enzyme that is different from that which phosphorylates CS-87 in vivo, typically thymidine kinase. Examples of other kinase enzymes are cytosine kinase, guanosine kinase, adenosine kinase, deoxycytidine kinase, 5xe2x80x2-nucleotidase, and deoxyguanosine kinase. For that reason, for example, it is preferred that CS-87 not be administered in combination with AZT or D4T, although the CS-87 can be use as salvage therapy against multiple resistant HIV cell lines that are resistant to AZT or D4T.